Apparatus and methods for keeping immersion fluid adjacent to an optical assembly during wafer exchange in an immersion lithography machine

ABSTRACT

Apparatus and methods keep immersion liquid in a space adjacent to an optical assembly. An optical assembly projects an image onto a substrate supported adjacent to the optical assembly by a substrate table. An insertion member insertable into the space between the optical assembly and the substrate, the substrate table, or both, divides the immersion liquid into a first portion and a second portion, the first portion disposed between the optical assembly and the insertion member, and the second portion disposed between the insertion member and the substrate, the substrate table, or both. The insertion member keeps the optical assembly in contact with the first portion when the substrate is moved away from being disposed adjacent to the optical assembly.

This is a divisional of U.S. patent application Ser. No. 11/976,898filed Oct. 29, 2007, which claims the benefit of U.S. ProvisionalApplication No. 60/918,057 filed Mar. 15, 2007. The disclosure of eachof the prior applications is incorporated herein by reference in itsentirety.

BACKGROUND

Lithography systems are commonly used to transfer images from a reticleonto a semiconductor wafer during semiconductor processing. A typicallithography system includes an optical assembly, a reticle stage forholding a reticle defining a pattern, a wafer stage assembly thatpositions a semiconductor wafer, and a measurement system that preciselymonitors the position of the reticle and the wafer. During operation, animage defined by the reticle is projected by the optical assembly ontothe wafer. The projected image is typically the size of one or more dieon the wafer. After an exposure, the wafer stage assembly moves thewafer and then another exposure takes place. This process is repeateduntil all the die on the wafer are exposed. The wafer is then removedand a new wafer is exchanged in its place.

Immersion lithography systems utilize a layer of immersion fluid thatcompletely fills a space between the optical assembly and the waferduring the exposure of the wafer. The optic properties of the immersionfluid, along with the optical assembly, allow the projection of smallerfeature sizes than is currently possible using standard opticallithography. For example, immersion lithography is currently beingconsidered for next generation semiconductor technologies includingthose beyond 45 nanometers. Immersion lithography therefore represents asignificant technological breakthrough that enables the continued use ofoptical lithography.

After a wafer is exposed, it is removed and exchanged with a new wafer.As contemplated in some immersion systems, the immersion fluid would beremoved from the space and then replenished after the wafer isexchanged. More specifically, when a wafer is to be exchanged, the fluidsupply to the space is turned off, the fluid is removed from the space(i.e., by vacuum), the old wafer is removed, a new wafer is aligned andplaced under the optical assembly, and then the space is re-filled withfresh immersion fluid. Once all of the above steps are complete,exposure of the new wafer can begin. In a tandem (or twin) stageimmersion lithography system, a pair of wafer stages are provided, withthe stages being alternately positioned under the optical assembly whilewafer exchange and/or alignment is performed on the wafer stage notdisposed under the optical assembly. When the exposure of the waferunder the optical assembly is complete, the two stages are swapped andthe process is repeated. Examples of such exposure apparatus aredisclosed in U.S. Pat. No. 6,341,007 and in U.S. Pat. No. 6,262,796, thedisclosures of which are incorporated herein by reference in theirentireties.

Wafer exchange with immersion lithography as described above continuesto be problematic for a number of reasons. The repeated filling anddraining of the space may cause bubbles to form within the immersionfluid. Bubbles may interfere with the projection of the image on thereticle onto the wafer, thereby reducing yields. The overall processalso involves many steps and is time consuming, which reduces theoverall throughput of the machine.

For examples of systems which reduce the overall throughput of themachine, see U.S. 2006/0023186 A1 and U.S. 2005/0036121 A1, thedisclosures of which are incorporated herein by reference in theirentireties.

SUMMARY

An apparatus and method for keeping immersion fluid in the spaceadjacent to the projection optical system when the wafer stage and/orthe wafer table moves away from the projection optical system, forexample during wafer exchange and/or during long fast moves, aretherefore desirable. Furthermore, an apparatus and method in which oneor more object is positioned opposite to the projection optical systemto keep immersion fluid in a space between the projection optical systemand the one or more objects, when moving the wafer stage and/or wafertable away from the projection optical system, are desirable. As aresult, machine throughput can be increased.

According to one aspect, the apparatus includes an optical assembly thatprojects an image onto a substrate and a stage assembly including asubstrate table that supports the substrate adjacent to the opticalassembly. An environmental system is provided to supply an immersionfluid to and remove the immersion fluid from the space between theoptical assembly and the substrate on the stage assembly. A movableinsertion member removably insertable into the space between the opticalassembly and the substrate, the substrate table, or both, is provided todivide the immersion fluid into a first portion and a second portion.The first portion is disposed between the optical assembly and theinsertion member, and the second portion is disposed between theinsertion member and the substrate, the substrate table, or both. Theinsertion member keeps the optical assembly in contact with the firstportion of the immersion fluid when moving the substrate and/or thesubstrate table away from being disposed adjacent to the opticalassembly. An exchange system removes the substrate from the substratetable and replaces it with a second substrate. Because of the insertionmember, the space does not have to be fully refilled with immersionfluid when the second substrate is positioned adjacent to the opticalassembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of an immersion lithography machine;

FIGS. 2A and 2B are a cross section and a plan view of an immersionlithography machine according to one embodiment;

FIGS. 3A to 3D illustrate further details of the movable insertionmember of the immersion lithography machine according the embodiment ofFIGS. 2A and 2B;

FIGS. 4A and 4B are plan views of two different twin wafer stagesaccording to other embodiments;

FIGS. 5A and 5B illustrate a further embodiment of the movable insertionmember;

FIG. 6A is a flow chart that outlines a process for manufacturing asubstrate; and

FIG. 6B is a flow chart that outlines substrate processing in moredetail.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 is a schematic illustration of a lithography machine 10. Thelithography machine 10 includes a frame 12, an illumination system 14(irradiation apparatus), an optical assembly 16, a reticle stageassembly 18, a substrate stage assembly 20, a measurement system 22, acontrol system 24, and a fluid environmental system 26. The design ofthe components of the lithography machine 10 can be varied to suit thedesign requirements of the lithography machine 10.

In one embodiment, the lithography machine 10 is used to transfer apattern (not shown) of an integrated circuit from a reticle 28 onto asemiconductor wafer 30 (illustrated in phantom). The lithography machine10 mounts to a mounting base 32, e.g., the ground, a base, or floor orsome other supporting structure.

In various embodiments, the lithography machine 10 can be used as ascanning type photolithography system that exposes the pattern from thereticle 28 onto the wafer 30 with the reticle 28 and the wafer 30 movingsynchronously. In a scanning type lithographic machine, the reticle 28is moved perpendicularly to an optical axis of the optical assembly 16by the reticle stage assembly 18, and the wafer 30 is movedperpendicularly to the optical axis of the optical assembly 16 by thewafer stage assembly 20. Exposure occurs while the reticle 28 and thewafer 30 are moving synchronously.

Alternatively, the lithography machine 10 can be a step-and-repeat typephotolithography system that performs exposure while the reticle 28 andthe wafer 30 are stationary. In the step and repeat process, the wafer30 is in a constant position relative to the reticle 28 and the opticalassembly 16 during the exposure of an individual field. Subsequently,between consecutive exposure steps, the wafer 30 is consecutively movedwith the wafer stage assembly 20 perpendicularly to the optical axis ofthe optical assembly 16 so that the next field of the wafer 30 isbrought into position relative to the optical assembly 16 and thereticle 28 for exposure. Following this process, the image on thereticle 28 is sequentially exposed onto the fields of the wafer 30.

However, the use of the lithography machine 10 provided herein is notnecessarily limited to a photolithography for semiconductormanufacturing. The lithography machine 10, for example, can be used asan LCD photolithography system that exposes a liquid crystal displaysubstrate pattern onto a rectangular glass plate or a photolithographysystem for manufacturing a thin film magnetic head. Accordingly, theterm “substrate” is generically used herein to refer to any device thatmay be patterned using lithography, such as but not limited to wafers orLCD substrates.

The apparatus frame 12 supports the components of the lithographymachine 10. The apparatus frame 12 illustrated in FIG. 1 supports thereticle stage assembly 18, the wafer stage assembly 20, the opticalassembly 16 and the illumination system 14 above the mounting base 32.

The illumination system 14 includes an illumination source 34 and anillumination optical assembly 36. The illumination source 34 emits abeam (irradiation) of light energy. The illumination optical assembly 36guides the beam of light energy from the illumination source 34 to theoptical assembly 16. The beam illuminates selectively different portionsof the reticle 28 and exposes the wafer 30. In FIG. 1, the illuminationsource 34 is illustrated as being supported above the reticle stageassembly 18. Typically, however, the illumination source 34 is securedto one of the sides of the apparatus frame 12 and the energy beam fromthe illumination source 34 is directed to above the reticle stageassembly 18 with the illumination optical assembly 36.

The illumination source 34 can be, for example, a g-line source (436nm), an i-line source (365 am), a KrF excimer laser (248 nm), an ArFexcimer laser (193 nm) or a F₂ laser (157 nm). Alternatively, theillumination source 34 can generate an x-ray.

The optical assembly 16 projects and/or focuses the light passingthrough the reticle 28 to the wafer 30. Depending upon the design of thelithography machine 10, the optical assembly 16 can magnify or reducethe image illuminated on the reticle 28. The optical assembly 16 neednot be limited to a reduction system. It also could be a 1× or greatermagnification system.

Also, with an exposure substrate that employs vacuum ultravioletradiation (VUV) of wavelength 200 nm or lower, use of a catadioptrictype optical system can be considered. Examples of a catadioptric typeof optical system are disclosed in U.S. Pat. No. 5,668,672, as well asU.S. Pat. No. 5,835,275. In these cases, the reflecting optical systemcan be a catadioptric optical system incorporating a beam splitter andconcave mirror. U.S. Patent No. 5,689,377 as well as European PatentApplication Publication No. EP 816892 A2 also use areflecting-refracting type of optical system incorporating a concavemirror, etc., but without a beam splitter, and also can be employed withthis embodiment. The disclosures of the above-mentioned U.S. patents, aswell as the European patent application publication are incorporatedherein by reference in their entireties.

The reticle stage assembly 18 holds and positions the reticle 28relative to the optical assembly 16 and the wafer 30. In one embodiment,the reticle stage assembly 18 includes a reticle stage 38 that retainsthe reticle 28 and a reticle stage mover assembly 40 that moves andpositions the reticle stage 38 and reticle 28.

Each stage mover assembly 40, 44 (44 being for the substrate) can movethe respective stage 38, 42 with three degrees of freedom, less thanthree degrees of freedom, or more than three degrees of freedom. Forexample, in alternative embodiments, each stage mover assembly 40, 44can move the respective stage 38, 42 with one, two, three, four, five orsix degrees of freedom. The reticle stage mover assembly 40 and thesubstrate stage mover assembly 44 can each include one or more movers,such as rotary motors, voice coil motors, linear motors utilizing aLorentz force to generate drive force, electromagnetic movers, planarmotors, or other force movers.

In photolithography systems, when linear motors (see U.S. Pat. Nos.5,623,853 or 5,528,118 which are incorporated by reference herein intheir entireties) are used in the wafer stage assembly or the reticlestage assembly, the linear motors can be either an air levitation typeemploying air bearings or a magnetic levitation type using Lorentz forceor reactance force. Additionally, the stage could move along a guide, orit could be a guideless type stage that uses no guide.

Alternatively, one of the stages could be driven by a planar motor,which drives the stage by an electromagnetic force generated by a magnetunit having two-dimensionally arranged magnets and an armature coil unithaving two-dimensionally arranged coils in facing positions. With thistype of driving system, either the magnet unit or the armature coil unitis connected to the stage base and the other unit is mounted on themoving plane side of the stage.

Movement of the stages as described above generates reaction forces thatcan affect performance of the photolithography system. Reaction forcesgenerated by the wafer (substrate) stage motion can be mechanicallytransferred to the floor (ground) by use of a frame member as describedin U.S. Pat. No. 5,528,100. Additionally, reaction forces generated bythe reticle (mask) stage motion can be mechanically transferred to thefloor (ground) by use of a frame member as described in U.S. Pat. No.5,874,820. The disclosures of U.S. Pat. Nos. 5,528,100 and 5,874,820 areincorporated herein by reference in their entireties.

The measurement system 22 monitors movement of the reticle 28 and thewafer 30 relative to the optical assembly 16 or some other reference.With this information, the control system 24 can control the reticlestage assembly 18 to precisely position the reticle 28 and the substratestage assembly 20 to precisely position the wafer 30. The design of themeasurement system 22 can vary. For example, the measurement system 22can utilize multiple laser interferometers, encoders, mirrors, and/orother measuring devices.

The control system 24 receives information from the measurement system22 and controls the stage assemblies 18, 20 to precisely position thereticle 28 and the wafer 30. Additionally, the control system 24 cancontrol the operation of the components of the environmental system 26.The control system 24 can include one or more processors and circuits.

The environmental system 26 controls the environment in a space (notshown) between the optical assembly 16 and the wafer 30. The spaceincludes an imaging field. The imaging field includes the area adjacentto the region of the wafer 30 that is being exposed and the area inwhich the beam of light energy travels between the optical assembly 16and the wafer 30. With this design, the environmental system 26 cancontrol the environment in the imaging field. The desired environmentcreated and/or controlled in the space by the environmental system 26can vary accordingly to the wafer 30 and the design of the rest of thecomponents of the lithography machine 10, including the illuminationsystem 14. For example, the desired controlled environment can be aliquid such as water. Alternatively, the desired controlled environmentcan be another type of fluid such as a gas. In various embodiments, thespace may range from 0.1 mm to 10 mm in height between top surface ofthe wafer 30 and the last optical element of the optical assembly 16.

In one embodiment, the environmental system 26 fills the imaging fieldand the rest of the space with an immersion fluid. The design of theenvironmental system 26 and the components of the environmental system26 can be varied. In different embodiments, the environmental system 26delivers and/or injects immersion fluid into the space using spraynozzles, electro-kinetic sponges, porous materials, etc. and removes thefluid from the space using vacuum pumps, sponges, and the like. Theenvironmental system 26 confines the immersion fluid in the space belowthe optical assembly 16. The environmental system 26 forms part of theboundary of the space between the optical assembly 16 and one or moreobjects, for example the wafer 30, the wafer stage assembly 20, or both.The immersion fluid confined by the environmental system 26 covers alocalized area on a surface of the wafer 30, the wafer stage assembly20, or both. The design of the environmental system 26 can vary. Forexample, it can inject the immersion fluid at one or more locations ator near the space. Further, the immersion fluid system can assist inremoving and/or scavenging the immersion fluid at one or more locationsat or near the wafer 30, the space and/or the edge of the opticalassembly 16. For additional details on various environmental systems,see, for example, U.S. 2007/0046910 A1, U.S. 2006/0152697 A1, U.S.2006/0023182 A1 and U.S. 2006/0023184 A1, the disclosures of which areincorporated herein by reference in their entireties.

Referring to FIGS. 2A and 2B, a cross section and a plan (overhead) viewof an immersion lithography machine illustrating one embodiment areshown. The lithography machine 200 includes an optical assembly 16 and astage assembly 202 that includes a wafer table 204 and a wafer stage206. The wafer table 204 is configured to support a wafer 208 (or anyother type of substrate) under the optical assembly 16. An environmentalsystem 26, surrounding the optical assembly 16, is used to supply andremove immersion fluid 212 from the space between the wafer 208 and thelower most optical element of the optical assembly 16. A substrateexchange system 216, including a wafer loader 218 (i.e., a robot) and analignment tool 220 (for example, a microscope and CCD camera), isconfigured to remove the wafer 208 on the wafer table 204 and replace itwith a second wafer. This is typically accomplished using the waferloader 218 to remove the wafer 208 from the wafer table 204.Subsequently, the second wafer (not shown) is placed onto the waferloader 218, aligned using the alignment tool 220, and then positionedunder the optical assembly 16 on the wafer table 204. As bestillustrated in FIG. 2B, a set of motors 222 are used to move the waferassembly 202 including the wafer table 204 and wafer stage 206 in up tosix degrees of freedom (X, Y, Z, θ_(X), θ_(y), θ_(z)) during operation.As noted above, the motors 222 can be any type of motors, such as linearmotors, rotary motors, voice coil motors, etc.

The immersion lithography machine 200 also includes an insertion memberpositioning system 224 that is configured to maintain some of theimmersion fluid 212 in a space below the optical assembly 16 while thewafer table 204 is away from under the optical assembly 16 (e.g., duringwafer exchange, alignment and long fast moves of the substrate away fromthe optical system). The insertion member positioning system 224includes a movable insertion member 226, a motor 228, and a controlsystem 230. The movable insertion member 226 is movable into the spacebetween the wafer 208, the wafer table 204, or both, and the lower mostoptical element of the optical assembly 16, so as to be positionedadjacent to and between the optical assembly 16 and a wafer 208 on thewafer table 204. Specifically, the movable insertion member 226 ismovable into the space between the wafer 208, the wafer table 204, orboth, and the lower end portion of the environmental system 26, so as tokeep the immersion fluid 212 in the space between the movable insertionmember 226 and the optical assembly 16. In this position, as will bediscussed below, the movable insertion member 226 causes a portion ofthe immersion liquid 212 to be trapped between the optical assembly 16and the insertion member 226. The movable insertion member 226 also isremovable from (i.e., out of) the space between the wafer 208 and thelower most optical element of the optical assembly 16. Thus, in theembodiment of FIGS. 2A and 2B, after the movable insertion member 226 isinserted into the space between the wafer 208 and the lower most opticalelement of the optical assembly 16, the movable insertion member 226 isnot released from the motor 228 by the control system 230. That is, themovable insertion member 226 remains attached to the motor 228 (i.e.,held by the control system 230) in the position adjacent to and betweenthe optical assembly 16 and a wafer 208 on the wafer table 204. Themovable insertion member 226 is held adjacent to the projection system16 without contacting the projection system 16 after the movableinsertion member 226 is moved into the space between the projectionsystem 16 and the substrate wafer 208. The movable insertion member 226is movable in up to six degrees of freedom directions using one or moremotors 228, which are controlled by the control system 230. The motor228 can be any type of motor. The movable insertion member 226 ispositioned under (adjacent to) the optical assembly 16 before the wafertable 204 (the wafer stage 206) and the held wafer is moved away frombeing under the optical assembly 16.

FIGS. 3A to 3D illustrate an example of how the movable insertion member226 keeps the optical assembly 16 in contact with at least a portion ofthe immersion liquid 212. As shown in FIG. 3A, immersion liquid 212 iscontinuously supplied to the immersion fluid element (liquid confinementmember) 310 of the environmental system 26 around the last opticalelement of the optical assembly 16, and is continuously recoveredthrough the recovery element 320, which may be a porous media vacuum,etc., of the environmental system 26. The recovery element 320 (porousmedia) is provided at the lower surface of the immersion fluid element310. In FIG. 3A, the wafer 208 is opposite to the optical assembly 16and the immersion fluid element 310 (and the recovery element 320).Further, the wafer table 204 or both the wafer 208 and the wafer table204 may be positioned under the optical assembly 16 and the immersionfluid element 310 (and the recovery element 320). At this time, themovable insertion member 226 is disposed outside of the space betweenthe optical assembly 16 and the wafer 208. Before a wafer exchange,during which the wafer table 204 moves away from the optical assembly16, the immersion liquid 212 should be removed from the wafer stage 206.Accordingly, the control system 230 directs the motor 228 to move themovable insertion member 226 into the space between the wafer 208 andthe lower most optical element of the optical assembly 16. Specifically,the movable insertion member 226 is moved into the space between thewafer 208 and the lower end of the immersion fluid element 310. As shownin FIG. 3B, the movable insertion member 226 divides the immersionliquid 212 in the space into a first portion between the opticalassembly 16 and the insertion member 226, and a second portion betweenthe insertion member 226 and the wafer 208. Thus, the movable insertionmember 226 keeps the optical assembly 16 in contact with the firstportion of the immersion liquid 212 when the wafer 208 is moved away(via movement of the wafer stage 206) from being disposed adjacent tothe optical assembly 16. In FIG. 3B, the first portion includes thespace between the wafer 208 and the immersion fluid element 310. Bymoving the wafer 208, as shown in FIG. 3C, the immersion liquid 212under the movable insertion member 226 can be removed through the porousmedia 320 of the immersion fluid element 310. When moving the wafer 208,the liquid 212 may be removed from a recovery outlet (not shown)provided on the wafer table 204 and/or a recovery outlet (not shown)provided on the back surface and/or the side surface of the moveableinsertion member 226. After all the immersion liquid 212 is recoveredfrom the wafer 208, shown in FIG. 3D, the wafer stage 206 can move longdistances at maximum speed without having liquid escaping from theimmersion fluid element 310. In addition, because no liquid is left onthe wafer 208 or wafer stage 206, no liquid will be scattered due to themovement of the wafer stage 206. Processes like wafer alignment andwafer 208 unload/exchange can be performed at this time. After the newwafer has been aligned using one or more alignment tools 220, the wafertable 204 is repositioned under the optical assembly 16. Preferably, thewafer table 204 is positioned under the movable insertion member 226.The control system 230 then directs the motor 228 to retract the movableinsertion member 226 from the space, preventing the escape of theimmersion liquid 212 from adjacent the optical assembly 16, and to movethe movable insertion member 226 to the position outside the space asshown in FIG. 3A. As a result, the space between the new wafer and theoptical assembly 16 is filled with the immersion liquid 212. Exposure isthen performed. In this manner, the insertion member positioning system224 maintains the immersion liquid 212 adjacent to the lower mostelement of the optical assembly 16 during wafer exchange and during longfast moves of the substrate away from the optical assembly.

In various embodiments, the control system 230 may be a separate controlsystem or it can be integrated into the control system used to controlthe exposure apparatus. Vertical position and/or tilt of at least one ofthe wafer table 204 and the movable insertion member 226 may be adjustedas needed before, during or after the wafer table 204 is moved out fromunder the optical assembly 16. The operation that is performed when thewafer table 204 is away from the optical assembly 16 is not limited to awafer exchange operation. For example, an alignment operation, ameasurement operation or other operations that involve long fast movesof the substrate or the wafer table may be executed while maintainingthe immersion liquid 212 in the space between the movable insertionmember 226 and the optical assembly 16.

FIGS. 4A and 4B are plan views of two different twin stage immersionlithography systems according to other embodiments. For the basicstructure and operation of the twin stage lithography systems, see U.S.Pat. No. 6,262,796 and U.S. Pat. No. 6,341,007. The disclosures of U.S.Pat. No. 6,262,796 and U.S. Pat. No. 6,341,007 are incorporated hereinby reference in their entireties. In both embodiments, a pair of waferstages WS1 and WS2 are shown. Motors 502 are used to move or positionthe two stages WS1 and WS2 in the horizontal direction (in thedrawings), whereas motors 504 are used to move or position the stagesWS1 and WS2 in the vertical direction (in the drawings). The motors 502and 504 are used to alternatively position one stage under the opticalassembly 16 while a wafer exchange and alignment is performed on theother stage. When the exposure of the wafer under the optical assembly16 is complete, then the two stages are swapped and the above process isrepeated. With either configuration, the various embodiments formaintaining immersion liquid in the space under the optical assembly 16as described and illustrated above with regard to FIGS. 2A through 3B,can be used with either twin stage arrangement. With regard to theembodiment of FIGS. 2A and 2B for example, a single movable insertionmember 226, motor 228, and control system 230 could be used adjacent tothe optical assembly 16. The movable insertion member 226 is movableseparately from the stages WS1 and WS2. When stages WS1 and WS2 are tobe swapped, the movable insertion member 226 is moved into the spacebetween the optical assembly 16 and the wafer 208 to maintain theimmersion liquid 212 below the optical assembly 16. During a transitionfrom a first state in which one of the stages WS1 and WS2 is positionedunder the optical assembly 16 to a second state in which the other ofthe stages WS1 and WS2 is positioned under the optical assembly 16, themovable insertion member 226 is positioned under the optical assembly 16and the space between the optical assembly 16 and the movable insertionmember 226 is filled with the immersion liquid 212.

In the various embodiments described above, the movable insertion membercan be made of a number of different materials, such as ceramic, metaland plastic. Because the movable insertion member is relatively thin andshould not be deformed under a load or during an operation, it ispreferable that the materials have a high stiffness that is resistant todeformation. The moveable insertion member may have a thickness of 50microns to 5 mm. Preferably, the thickness ranges from 50 microns to 200microns. These materials also may be coated with Teflon according toother embodiments. The size of the movable insertion member also shouldbe sufficient to cover the area occupied by the immersion liquid. In thevarious embodiments described above, the surface of the last opticalelement of the optical assembly 16 is constantly under immersion fluidenvironment, preventing the formation of a fluid mark (e.g. “a watermark”). In addition, the insertion member is moved, for example, by arobot arm or other actuator.

In some embodiments, the top surface (facing the optical assembly 16)and the bottom surface (facing the wafer 208) of the movable insertionmember 226 neither repel nor attract liquid. In other embodiments, thetop surface of the movable insertion member 226 attracts liquid (e.g.,is hydrophilic) and the bottom surface of the movable insertion member226 repels liquid (e.g., is hydrophobic). In a further embodiment, shownin FIGS. 5A and 5B, the bottom surface of the movable insertion member226 is hydrophobic, and a hydrophobic bead 501 (not shown to scale) isprovided around the perimeter of the top surface of the movableinsertion member 226. The top surface of the movable insertion member226 inside the hydrophobic bead 501 is hydrophilic.

Semiconductor wafers can be fabricated using the above describedsystems, by the process shown generally in FIG. 6A. In step 601 thesubstrate's function and performance characteristics are designed. Next,in step 602, a mask (reticle) having a pattern is designed according tothe previous designing step, and in a parallel step 603 a wafer is madefrom a silicon material. The mask pattern designed in step 602 isexposed onto the wafer from step 603 in step 604 by a photolithographysystem described hereinabove. In step 605 the semiconductor substrate isassembled (including the dicing process, bonding process and packagingprocess). Finally, the substrate is then inspected in step 606.

FIG. 6B illustrates a detailed flowchart example of the above-mentionedstep 504 in the case of fabricating semiconductor substrates. In FIG.6B, in step 611 (oxidation step), the wafer surface is oxidized. In step612 (CVD step), an insulation film is formed on the wafer surface. Instep 613 (electrode formation step), electrodes are formed on the waferby vapor deposition. In step 614 (ion implantation step), ions areimplanted in the wafer. The above mentioned steps 611-614 form thepreprocessing steps for wafers during wafer processing, and selection ismade at each step according to processing requirements.

At each stage of wafer processing, when the above-mentionedpreprocessing steps have been completed, the following post-processingsteps are implemented. During post-processing, first, in step 615(photoresist formation step), photoresist is applied to a wafer. Next,in step 616 (exposure step), the above-mentioned exposure substrate isused to transfer the circuit pattern of a mask (reticle) to a wafer.Then in step 617 (developing step), the exposed wafer is developed, andin step 618 (etching step), parts other than residual photoresist(exposed material surface) are removed by etching. In step 619(photoresist removal step), unnecessary photoresist remaining afteretching is removed.

Multiple circuit patterns are formed by repetition of thesepreprocessing and post-processing steps.

While the particular lithography machines as shown and disclosed hereinare fully capable of obtaining the objects and providing the advantagesherein before stated, it is to be understood that they are merelyillustrative embodiments of the invention, and that the invention is notlimited to these embodiments.

1. A lithographic projection apparatus comprising: a projection opticalassembly having a final optical element; a stage assembly including asubstrate table on which a substrate is supported; a confinement memberwhich encircles a portion of a path of an exposure beam under the finaloptical element of the projection optical assembly; and a movable memberwhich is movable in a space between the confinement member and thesubstrate, the substrate table, or both, the space being divided by themovable member into a first portion between the confinement member andthe movable member and a second portion between the movable member andthe substrate, the substrate table, or both, wherein the substratesupported by the substrate table is exposed with an exposure beam fromthe final optical element of the projection optical assembly through animmersion liquid, and the immersion liquid in the second portion isremoved via the confinement member.